The present disclosure relates generally to wireless networking such as Long Term Evolution (LTE) systems. The 3rd Generation Partnership Project (3GPP) specifies User Equipment (UE) power classes in 3GPP TS 36.101 Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception (Release 8 (December 2008), Release 9 (December 2009), Release 10 (March 2011), Release 11 (September 2012), and Release 12 (ongoing)), the contents of which are incorporated by reference herein. A higher power class with 31 dBm (1.2 W) has recently been introduced to 3GPP TS 36.101 v11.3.0 (February 2013), i.e. power class 1 for E-UTRA band 14. This power class complements the existing 23 dBm power class 3 UE currently defined in the 3GPP standard. The main motivation behind this higher power class is range extension in rural deployments, as the LTE link budget is typically uplink limited in noise-limited environments. However, a High Power UE (HPUE) can also enhance coverage in suburban and urban areas, especially indoor, in tunnels and in parking garages, due to terrain, etc. This higher power class today is for vehicular modems, but it is expected to evolve to mobile devices and the like.
Disadvantageously, there are Uplink (UL) interference concerns if HPUEs are deployed in areas where the evolved Node B (eNB) density was designed for 23 dBm power class UE coverage. Following conventional 3GPP open loop UE power control behavior, an HPUE will reach max power well before it is necessary from a range extension perspective thereby improving throughput for that device, but increasing UL interference noise rise and degrading UL performance overall from a system perspective. LTE is typically deployed with a frequency reuse of one, similar to code division multiple access (CDMA), where the same frequency bands are used in every cell, and thus, while the HPUE is advantageous for range extension, it can cause problematic interference when used for increased throughput.
As the primary intent behind the HPUE was for range extension, not increased throughput, a mechanism is needed to limit UE transmit power such that higher power (more than, for example, 23 dBm) is utilized only to extend range/coverage, not to increase throughput, so that the benefit of HPUE can still be utilized in poor coverage spots (indoor/tunnels, etc.) in urban/suburban areas without causing unnecessary UL interference. Accordingly, there is a need for a method and apparatus for UE power class adaptation for coverage extension in LTE.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.